Got reclassed to 25u. Any insight on the career, a lot of field or more office, advice on career path and schools?

Get 25B as a secondary, it will help for broader growth and movement.
As a 25 U, B, L. I've used all three to get me where I am and wanted to be. I started as a 25L in artillery till it got phased out with 25U's . Later I noticed 25Bs in the TOC and working with servers and thought to myself what if I could do that when I get out? So I went 25B. Used it to move to different jobs at E4, E5, E6. I'll admit I haven't seen much E7 25B unless your in a signal Company. E7 25U are at Every Combat Arms BN guaranteed. I choose to go to 25L ALC because I wanted to learn Fiber again and SLC.
Let me finish this up by saying 25U is the jack of all 25 Series MOS's and master of NONE!.
You will learn a little of Every one else's MOS just enough to be dangerous. Dont get cocky. If you got any questions hit me up going on 19 years of being a wigwam.

Good MOS with career prospects IN and OUT of the service. Tough training. Work hard.

Really depends on the units you go to. My time as a 25U was spent station in a light infantry unit where we spent most our time in the field or preparing for the field. Most of the schools will be communications related. There is an Army program that allows 25Us to go and work at the company Harris to gain experience. I'm sure you can find it with a quick Google search.